JPS5917063A - Worm gear - Google Patents

Abstract

PURPOSE:To allow a worm gear to attain its specified range of regular wear in possibly earlier stage by forming a film, equipped with solid lubricating performance, over the surface of either the worm or worm wheel and thereby obtaining the early flank fit before the flanks wear too much. CONSTITUTION:For promotion of the early flank fit, a soft metal, solid lubricant or synthetic resin equipped with solid lubricating performance is applied to the flank of either a worm or worm wheel by means of plating, casting, sintering, coating, spraying or adhesion. Compared with operation without such a coating as shown by A, the one with a film as shown by B indicates an early coming into the regular wear range as B', where the flank film resides in the bottoms of surface roughness to give apparently the same effect as that the thickness of oil film formed between the contact surfaces has increased. Thus the rate of wear in the regular wear range will lessen.

Description

[Detailed description of the invention] Initial tooth surface 1! The present invention relates to a warm carrier that can cause Jllll staining and reach the steady wear region at an early stage.

A well-known worm carrier is a worm D as shown in FIG.
1 and a worm wheel 02, and the rotation of the worm shaft 03 imparts rotation to a worm wheel shaft (not shown) through tooth surface engagement.

FIG. 2 shows the meshing state of the tooth surfaces in a sectional view taken in a direction perpendicular to the axis of the worm wheel 02 in FIG. 1. In Fig. 2, the worm G 1 (
A case is shown in which the worm wheel 02 is driven and rotated in the direction of arrow A using a JIS S-shaped tooth profile as an example.

Note that the arrowhead indicates the rotation direction of the worm shaft 03 and the worm 01.

As is well known, the meshing of a worm gear is similar to that of an inholute gear in which the worm 01 is placed on a rack in a cross section perpendicular to the axis of the worm wheel 02, and the tooth surfaces on this cross section are similar to the meshing of a normal gear. It may be a rolling or sliding contact, or when viewed from the 0 direction of the worm shaft, a sliding contact is made with the worm 01 surface serving as the threaded surface.

Therefore, due to the load movement, the worm tooth surface 01 becomes a spiral tooth contact area 04, as shown in FIG.
As shown in FIG. 6(B) (a), the worm wheel tooth surface 02 has a substantially rectangular arc-shaped tooth contact area 05, and the tooth profile cross section A of each of the worm 01 and the worm wheel 02,
-A and B-B are the 6th. As shown in Figure (A+ (b) and Figure 6 (B) (b), the normal tooth profile becomes concave due to tooth surface wear.

As shown in FIG. 4, these wear rates become almost constant (south face wear amount per unit time) after the initial run-in stage of the tooth surface. Here, (,O)p+ωG) increases the hacklash of the warmer. In FIG. 4, α indicates a tooth surface familiarization period, and β indicates a steady wear period.

This increase in backlash is caused by the rotation direction of the worm 01, in the forward or reverse circular direction, or by the load (worm shaft thrust l).
-) is a major drawback of various types of worm carriers, including machine tool parts and full-drive worm carriers, which have fluctuations in temperature.

To prevent this wear, taking the combination of hardened steel (approximately 550HB) worm 01 and copper alloy worm wheel 02 as an example, it is generally countered by increasing the hardness of the wheel 02 material (copper alloy). , as shown in Fig. 5, when the hardness of the worm wheel 02 side increases, the worm wheel 0
The amount of wear on the 1 side tooth surface (harder than the worm wheel 02 tooth surface) also increases, and the roughening of the worm 01 tooth surface (increase in surface roughness) accelerates the tooth surface wear of the worm wheel 02 tooth surface, which is made of copper alloy. and the worm wheel 02 tooth hardness.
- In many cases, the effect of simply increasing the height is not obtained. 3゜The present invention allows the tooth surface to become compliant before the tooth surface wears out significantly, and reaches the steady wear range of the worm gear as quickly as possible. This is a great way to provide a warm environment.

That is, the present invention provides at least one tooth surface of a worm or a worm wheel with a soft metal (generally referred to as having a hypothetical hardness of 100 or less, copper, tin, silver, gold, white metal, etc.) or solid lubricants (molyftene disulfide, graphite, etc.) or synthetic resins (fluoroethylene, fluororesins, phenol resins, polyimide resins, polyimide amide resins, etc.) by plating, casting, baking or Coating or spraying refers to the warm coating that characterizes the application.

In the worm carrier of the present invention, the worm material may include surface hardened and quenched materials such as alloy steel, carbon steel, and cast iron.
Sub-hardening or tempering can be used, and the worm wheel can be made of tempered materials such as copper alloy or cast iron.

In addition, lubricating oil (mineral oil, synthetic oil, etc.) is used to lubricate the meshing tooth surfaces.

Hereinafter, the warm carrier of the present invention will be explained in detail using specific examples.

The following experiment was conducted to specifically test the running-in effect shown by the decrease in surface roughness.1 The material corresponding to the worm and worm wheel used in the experiment was a combination of steel and copper alloy. Than! ! 1llll Stain-resistant steel - Oki] [Si size qM8 equivalent, 31DHB (H material) and 250H
B (S material)] was used. In addition, the test surface pressure is also the surface pressure of the worm carrier (usually steel-steel alloy combination, Hertzian stress Pmax at the meshing pitch point is 0 kgf/mm2
) is a much larger value.

The test was carried out using two cylinders (diameter 70 mm, 11-'-ra effective width 10
mm) rolling/sliding contact, and the slip rate is set to the low speed side (
S material) is approximately -25% of the high speed side (Hi) (H material -2100
rpm, 5i-170[) rpm), and 200 turbine oil was used as the lubricating oil.

Copper is used as a soft metal, and it is applied to H material by plating, and t is the ratio of H material base roughness Rmax and H to copper plating thickness t.
/Rmax, H-0 (&JI goldless), 0.25.1.
The machine was operated under four conditions of 0 and 2.5 until wear (rolling fatigue bit) occurred on the S material.

The results are shown in FIGS. 6(A) and (B). Figure 6 (A+
, (B) Medium, * is t/RmaX, H-0 (without W gold),
○ is t/RmaX, H-025, ■ is t/RmaX, H
-10, ■ is the result of t/RmaX, H-25, γ
The dotted line H shows the surface roughness of the H material before load operation, and the dotted line S shows the surface roughness of the S phase before load operation.

Focusing on the roughness of S material without copper plating, Figure 6 (B
), when the H material has copper plating, the roughness of the S material does not decrease and enters the steady wear range after long-term operation (106 times or more). Also, the roughness of H material is as shown in Fig. 6(A).
There was no particular increase in wear even when the load was operated at a higher surface pressure.

From the above, good effects were confirmed in the range of t/R7naX, H≦25. It has also been confirmed that even if the tooth surface is plated thicker than the above, the practical effect will not be diminished.

Furthermore, when similar experiments were conducted with other soft metals, solid lubricants, and synthetic resins as in the case of copper, it was confirmed that the same effects as in the case of copper can be obtained.

As shown in the above specific examples, at least one of the worm or the worm wheel has a soft metal having solid lubricating ability,
By forming a coating of solid lubricant and synthetic resin on the tooth surfaces, a zukokichi effect is created that reduces wear on each tooth surface. For example, as shown in Fig. 7, compared to the case without the above coating, the case with the above coating (■) enters the steady wear region earlier as shown in ■', and the tooth surface coating or the south surface roughness. This is similar to the increase in the thickness of the oil film that remains in the troughs and is apparently formed between the contact surfaces, and the wear rate in the steady wear area also decreases. (showing the steady wear area).

In addition, ■ in Fig. 7 indicates copper plating (t/Rmax
, H-10) on the worm, or other soft metals, solid lubricants, and synthetic resin coatings.
Furthermore, the same effect can be obtained even when the thickness of the coating is changed, and when the coating is provided on the worm wheel or both.

As described in detail above, the worm carrier of the present invention is extremely useful as a worm gear for machine tools and various other worm carriers.

[Brief explanation of the drawing]

Fig. 1 shows the configuration of a well-known worm carrier. Fig. 2 is a sectional view taken in the direction perpendicular to the axis of the worm wheel 02 in Fig. 1, and shows the meshing state of the tooth surfaces. Fig. 6 shows defects that occur in the well-known worm carrier. 6(A) (b).
) is a sectional view of the tooth profile at section 8-A in Fig. 6 (A) (a), Fig. 6 (B) (b) is a sectional view of the tooth profile at section BB in Fig. 3 (B) (a), and Fig. 4 The figure is a chart showing the defect shown in Fig. 3 in terms of the relationship between the worm car operation time and the amount of tooth surface wear.
4. Figure 1 is a chart for explaining the shortcomings of the conventional countermeasure method for this defect. Figures 6 (A), (B) and 7 are charts for explaining the effects of the present invention. be. Sub-Agents 1) Meifu Agent Ryo Hagiwara - Fig. 2 Fig. 3 Section - Mugiya driving time A - Mugwheel semi-offline stone history, '1fA
+m2 hertz stress P7+1CL engineering, Kgmuichi

Claims (1)

[Claims] A worm gear characterized in that a soft metal, a solid lubricant, or a synthetic resin is plated, cast, fired, coated, sprayed, or pasted on at least one of a worm or a worm wheel.